Street-network Sprawl in Brikama, Gambia

What is Street-network sprawl?

Street-network Sprawl is a way to measure urban sprawl, worldwide, through the connectedness of the streets. Less sprawl means more connected, more walkable streets. Well-connected streets – like New York City’s grid – are more walkable and can be served by public transit.

The street network is permanent, and its connectivity affects the livability and environmental footprint of cities for decades and centuries to come. In places with more connected streets, residents drive less and walk more. A well-connected street network is associated with better outcomes for health, the environment, sustainable consumption, social integration, and equity.

We can quantify how connected street networks are with the Street Network Disconnectedness Index (SNDi).

SNDi -- our measure of street-network sprawl (disconnectedness)

The SNDi is a comprehensive measurement of “sprawl”. It captures:

A higher SNDi means less-connected streets – i.e., more sprawl. For the 10137 cities in our dataset, the average SNDi is 2.25, with half of the cities' SNDis falling between 1.08 and 3.25.

More information on the sprawl index can be found in these research papers:

To see the state of street-network sprawl across the globe, visit the sprawlmap.

Brikama: city in Western, Gambia

What exactly constitutes the spatial extent of the city? For these aggregations, we used the Global Human Settlement Layer Urban Center Database (GHS-UCDB) to define the boundaries of the city. These cities -- or urban centers -- cover areas that are densely populated and built-up, and so may extend beyond the spatial borders of these cities that we may be familiar with. The GHS area is shaded in blue.

View Brikama, Gambia on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Brikama as of 2014, the overall level of street-network sprawl is -0.06, which is very well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are -0.26, -0.22, -0.02 and 0.99. In each period, new street development in Brikama steadily grows more disconnected than in the last.

Quantity of street network construction: The street network in Brikama spans a total of 327 kilometers. The period with the greatest volume of street construction was 1991-2000. These roads have an SNDi of -0.02, which is very well-connected.

Effect on the aggregate network: New construction in each period adds to the total stock of streets, but does not change streets that have already been built. Therefore, it has a limited effect on the street network as a whole. The SNDis of the aggregate street network in the respective time periods are -0.26, -0.25, -0.17 and -0.06. Overall, the SNDi of the aggregate street network has risen: the street network in Brikama has become more disconnected.

Brikama and Western follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these rose steadily.

How do development practices in Brikama fare in comparison to others in Western? Most recently in 2001-2014, street construction in Brikama was the 3rd-most disconnected out of the 3 cities in Western. Its position in the ranks since 1975 has fallen; relative to other cities in Western, street construction in Brikama has become more connected. Brikama ranked 2nd in 1975, 3rd in 1976-1990, 3rd in 1991-2000 and 3rd in 2001-2014.

Brikama and Gambia follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these rose steadily.

How do development practices in Brikama fare in comparison to others in Gambia? Most recently in 2001-2014, street construction in Brikama was the 3rd-most disconnected out of the 4 cities in Gambia. Its position in the ranks since 1975 has fallen; relative to other cities in Gambia, street construction in Brikama has become more connected. Brikama ranked 2nd in 1975, 4th in 1976-1990, 4th in 1991-2000 and 3rd in 2001-2014.

Brikama and Western follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Brikama is the 3rd-most disconnected out of the 3 cities in Western. Its position in the ranks since 1975 has fallen; relative to other cities in Western, the street network in Brikama has become more connected. Brikama ranked 2nd in 1975, 3rd in 1976-1990, 3rd in 1991-2000 and 3rd in 2001-2014.

Brikama and Gambia follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Brikama is the 4th-most disconnected out of the 4 cities in Gambia. Its position in the ranks since 1975 has fallen; relative to other cities in Gambia, the street network in Brikama has become more connected. Brikama ranked 2nd in 1975, 4th in 1976-1990, 4th in 1991-2000 and 4th in 2001-2014.

As of 2015, Brikama had a built-up area of 9.69 square kilometers, and a population of 127019 people.

These are some other cities with approximately the same population: